Alteration of fecal bacterial communities in weanling pigs fed diets supplemented with chicory, mannan oligosaccharides, or chitosan

Abstract Text: Our previous study demonstrated that dietary prebiotics did not affect growth performance and serum IgA of weanling pigs, except that feeding mannan oligosaccharides (MOS) decreased G:F compared to the other treatments. To determine changes in fecal bacterial communities, 64 weanling pigs were allotted to 16 pens with 4 dietary treatments. The control diet was a complex nursery diet and the additional 3 diets contained 0.1% chicory, 0.1% MOS, and 0.02% chitosan, respectively. Fecal samples from 2 pigs/pen were collected on d 0, 14, and 28 post-weaning to evaluate bacterial community composition using 16S rRNA tag sequencing. Database independent operational taxonomic unit (OTU) approach was used for bacterial community analysis. The α–diversity estimate (Chao 1) was different (P < 0.05) over time, but was not affected (P > 0.10) by treatment. Additionally, β-diversity changed over time (P < 0.05). On d 14, β-diversity of the bacterial community in control pigs were different (P < 0.05) from chicory and chitosan, but were not different (P > 0.10) from MOS. Linear discriminate analysis (LDA) by LEfSe was used for pair-wise comparisons of OTU abundances in the bacterial communities (|LDA score| > 2 was considered significant). On d 14, control and MOS had 26 and 12 OTUs, respectively more abundant in the 3 comparisons with other treatments, in which the majority of these OTUs belonged to family Lactobacillaceae. Additionally, 25 and 17 OTUs, respectively that predominantly belonged to family Ruminococcaceae and Christensenellaceae were associated with chicory and chitosan. Using multivariate association with linear models (MaAsLin; P < 0.05, q < 0.05), 3 OTUs belonging to Lactobacillaceae family were positively correlated to MOS (coeff. > 0.012). Mocosae spp. was associated (coeff. = 0.092) with IgA. One OTU belonging to family Christensenellaceae was negatively correlated (coeff. = -0.01) to BW. Family level classification of OTUs was analyzed using ANOVA1 of MATLAB. On d 14, Lactobacillaceae decreased (P < 0.05) in chicory (18.4%) compared to control (46.5%) and MOS (41.7%); whereas, Ruminoccocaceae increased (P < 0.05) in chicory (15.4%) and chitosan (15.0%) compared to control (10.6%) and MOS (10.3%). Chicory had greater (P < 0.05) Christensenellaceae (5.6%) compared to the other 3 treatments (< 1.8%). On d 28, Streptococcaceae increased (P< 0.05) in control (27.2%) compared to chicory (8.7%) and chitosan (9.5%). In conclusion, pigs fed MOS shared a similar bacterial community with control; however, bacterial communities in chicory and chitosan were similar.

Keywords: fecal bacteria, prebiotics, weanling pigs